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2018

Physical Sciences and Mathematics

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Articles 1 - 30 of 651

Full-Text Articles in Engineering

Transient Transmission Oscillations In Doped And Undoped Lithium Niobate Induced By Near-Infrared Femtosecond Pulses, Bryan J. Crossman, Gregory J. Taft Dec 2018

Transient Transmission Oscillations In Doped And Undoped Lithium Niobate Induced By Near-Infrared Femtosecond Pulses, Bryan J. Crossman, Gregory J. Taft

Physics Faculty Publications

Transient transmission oscillations in X-cut and Z-cut congruent, iron-doped, and magnesium-doped lithium niobate samples were measured using 50 fs, 800 nm, 0.5 nJ pulses from a self-mode-locked Ti:sapphire laser in an optical pump–probe system. Several Raman-active oscillation modes excited by these pulses were observed as changes in the transmitted probe intensity versus time delay between the pump and probe pulses. The samples were rotated to determine how the incident polarization of the pump pulses affects the mode excitations. The observed Raman-active oscillations correspond to previously reported symmetry modes measured with traditional, continuous-wave, Raman spectroscopy using the same scattering …

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Preface: Earth Observation For Integrated Water And Basin Management: Challenges For Adaptation To A Changing Environment, María J. Polo, Maria P. González-Dugo, Christopher M.U. Neale Dec 2018

Preface: Earth Observation For Integrated Water And Basin Management: Challenges For Adaptation To A Changing Environment, María J. Polo, Maria P. González-Dugo, Christopher M.U. Neale

Daugherty Water for Food Global Institute: Faculty Publications

Integrated river basin management involves a sound knowledge of water and land interactions, and impacts from and feedbacks to human activity. Remote sensing has been an efficient and increasingly promising means of gathering direct information of the Earth surface, as well as information on water and energy fluxes. The recent generation of high-resolution sensors offers a huge potential for monitoring, assessing, and modelling our changing environment in a context of uncertainty about how future climate conditions will affect the current water resource and basin management framework. Moreover, large amounts of data are now available posing a challenging opportunity to the …

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Monitoring The Impact Of Groundwater Pumping On Infrastructure Using Geographic Information System (Gis) And Persistent Scatterer Interferometry (Psi), Kirsten Deprekel, El Hachemi Bouali, Thomas Oommen Dec 2018

Monitoring The Impact Of Groundwater Pumping On Infrastructure Using Geographic Information System (Gis) And Persistent Scatterer Interferometry (Psi), Kirsten Deprekel, El Hachemi Bouali, Thomas Oommen

Department of Geological and Mining Engineering and Sciences Publications

Transportation infrastructure is critical for the advancement of society. Bridges are vital for an efficient transportation network. Bridges across the world undergo variable deformation/displacement due to the Earth’s dynamic processes. This displacement is caused by ground motion, which occurs from many natural and anthropogenic events. Events causing deformation include temperature fluctuation, subsidence, landslides, earthquakes, water/sea level variation, subsurface resource extraction, etc. Continual deformation may cause bridge failure, putting civilians at risk, if not managed properly. Monitoring bridge displacement, large and small, provides evidence of the state and health of the bridge. Traditionally, bridge monitoring has been executed through on-site surveys. …

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Coordinated Unmanned Aircraft System (Uas) And Ground-Based Weather Measurements To Predict Lagrangian Coherent Structures (Lcss), Peter J. Nolan, James Pinto, Javier González-Rocha, Anders Jensen, Christina N. Vezzi, Sean C. C. Bailey, Gijs De Boer, Constantin Diehl, Roger Laurence Iii, Craig W. Powers, Hosein Foroutan, Shane D. Ross, David G. Schmale Iii Dec 2018

Coordinated Unmanned Aircraft System (Uas) And Ground-Based Weather Measurements To Predict Lagrangian Coherent Structures (Lcss), Peter J. Nolan, James Pinto, Javier González-Rocha, Anders Jensen, Christina N. Vezzi, Sean C. C. Bailey, Gijs De Boer, Constantin Diehl, Roger Laurence Iii, Craig W. Powers, Hosein Foroutan, Shane D. Ross, David G. Schmale Iii

Mechanical Engineering Faculty Publications

Concentrations of airborne chemical and biological agents from a hazardous release are not spread uniformly. Instead, there are regions of higher concentration, in part due to local atmospheric flow conditions which can attract agents. We equipped a ground station and two rotary-wing unmanned aircraft systems (UASs) with ultrasonic anemometers. Flights reported here were conducted 10 to 15 m above ground level (AGL) at the Leach Airfield in the San Luis Valley, Colorado as part of the Lower Atmospheric Process Studies at Elevation—a Remotely-Piloted Aircraft Team Experiment (LAPSE-RATE) campaign in 2018. The ultrasonic anemometers were used to collect simultaneous measurements of …

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Riverbank Filtration Impacts On Post Disinfection Water Quality In Small Systems—A Case Study From Auburn And Nebraska City, Nebraska, Matteo D'Alessio, Bruce Dvorak, Chittaranjan Ray Dec 2018

Riverbank Filtration Impacts On Post Disinfection Water Quality In Small Systems—A Case Study From Auburn And Nebraska City, Nebraska, Matteo D'Alessio, Bruce Dvorak, Chittaranjan Ray

Daugherty Water for Food Global Institute: Faculty Publications

Small water systems can experience a fluctuating quality of water in the distribution system after disinfection. As chlorine is the most common disinfectant for small systems, the occurrence of disinfection byproducts (DBPs) represents a common problem for these systems. Riverbank filtration (RBF) can be a valuable solution for small communities located on riverbanks. The objectives of this study were to evaluate (i) the improvements in water quality at two selected RBF systems, and (ii) the potential lower concentrations of DBPs, in particular, trihalomethanes (THMs), in small systems that use RBF. Two small communities in Nebraska, Auburn and Nebraska City, using …

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Optimal Placement Of Distributed Energy Storage Systems In Distribution Networks Using Artificial Bee Colony Algorithm, Choton K. Das, Octavian Bass, Ganesh Kothapalli, Thair S. Mahmoud, Daryoush Habibi Dec 2018

Optimal Placement Of Distributed Energy Storage Systems In Distribution Networks Using Artificial Bee Colony Algorithm, Choton K. Das, Octavian Bass, Ganesh Kothapalli, Thair S. Mahmoud, Daryoush Habibi

Research outputs 2014 to 2021

The deployment of utility-scale energy storage systems (ESSs) can be a significant avenue for improving the performance of distribution networks. An optimally placed ESS can reduce power losses and line loading, mitigate peak network demand, improve voltage profile, and in some cases contribute to the network fault level diagnosis. This paper proposes a strategy for optimal placement of distributed ESSs in distribution networks to minimize voltage deviation, line loading, and power losses. The optimal placement of distributed ESSs is investigated in a medium voltage IEEE-33 bus distribution system, which is influenced by a high penetration of renewable (solar and wind) …

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Flow Analysis Through Collectorwell Laterals: A Case Study From Sonoma County Water Agency, California, Matteo D'Alessio, John Lucio, Ernest Williams, Donald Seymour, Jay Jasperse, Chittaranjan Ray Dec 2018

Flow Analysis Through Collectorwell Laterals: A Case Study From Sonoma County Water Agency, California, Matteo D'Alessio, John Lucio, Ernest Williams, Donald Seymour, Jay Jasperse, Chittaranjan Ray

Daugherty Water for Food Global Institute: Faculty Publications

The Sonoma County Water Agency (SWCA) uses six radial collector wells along the Russian River west of Santa Rosa, to provide water for several municipalities and water districts in north-western California. Three collector wells (1, 2, and 6) are located in the Wohler area, and three collector wells (3, 4, and 5) are located in the Mirabel area. The objective of this paper is to highlight the performance of the three collector wells located in the Mirabel area since their construction. The 2015 investigation showed a lower performance of Collectors 3 and 4 compared to their original performances after construction …

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First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir Dec 2018

First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir

Mechanical Engineering Faculty Research

We report the first observation of the parity-violating gamma-ray asymmetry A(gamma)(np) in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A(gamma)(np) isolates the Delta I = 1, S-3(1)-> P-3(1) component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory… See full text for full abstract.

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Assessing The Feasibility Of Soil Infiltration Trenches For Highway Runoff Control On The Island Of Oahu, Hawaii, Martina Sobotkova, Jaromir Dusek, Ghasem Alavi, Laxman Sharma, Chittaranjan Ray Dec 2018

Assessing The Feasibility Of Soil Infiltration Trenches For Highway Runoff Control On The Island Of Oahu, Hawaii, Martina Sobotkova, Jaromir Dusek, Ghasem Alavi, Laxman Sharma, Chittaranjan Ray

Daugherty Water for Food Global Institute: Faculty Publications

The coastal waters of Hawaii are extremely important for recreation as well as for the health of the marine environment. Non-point source pollution from storm runoff poses a great threat to surface water quality in Hawaii. The State of Hawaii Department of Transportation (HDOT) includes infiltration trenches as a best management practice (BMP) option to reduce pollution caused by stormwater runoff. HDOT guidelines state that the implementation of BMPs is needed to reduce sediment and pollutant loads to streams and the ocean. In this study, the suitability of soils adjacent to highways on Oahu for the siting of infiltration trenches …

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Paul Baran, Network Theory, And The Past, Present, And Future Of Internet, Christopher S. Yoo Dec 2018

Paul Baran, Network Theory, And The Past, Present, And Future Of Internet, Christopher S. Yoo

All Faculty Scholarship

Paul Baran’s seminal 1964 article “On Distributed Communications Networks” that first proposed packet switching also advanced an underappreciated vision of network architecture: a lattice-like, distributed network, in which each node of the Internet would be homogeneous and equal in status to all other nodes. Scholars who have subsequently embraced the concept of a lattice-like network approach have largely overlooked the extent to which it is both inconsistent with network theory (associated with the work of Duncan Watts and Albert-László Barabási), which emphasizes the importance of short cuts and hubs in enabling networks to scale, and the actual way, the Internet …

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Open Source Foundations For Spatial Decision Support Systems, Jochen Albrecht Dec 2018

Open Source Foundations For Spatial Decision Support Systems, Jochen Albrecht

Publications and Research

Spatial Decision Support Systems (SDSS) were a hot topic in the 1990s, when researchers tried to imbue GIS with additional decision support features. Successful practical developments such as HAZUS or CommunityViz have since been built, based on commercial desktop software and without much heed for theory other than what underlies their process models. Others, like UrbanSim, have been completely overhauled twice but without much external scrutiny. Both the practical and the theoretical foundations of decision support systems have developed considerably over the past 20 years. This article presents an overview of these developments and then looks at what corresponding tools …

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College Of Engineering Senior Design Competition Fall 2018, University Of Nevada, Las Vegas Dec 2018

College Of Engineering Senior Design Competition Fall 2018, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

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Simulating The Impacts Of Irrigation Levels On Soybean Production In Texas High Plains To Manage Diminishing Groundwater Levels, Vaishali Sharda, Prasanna H. Gowda, Gary Marek, Isaya Kisekka, Chittaranjan Ray, Pradip Adhikari Dec 2018

Simulating The Impacts Of Irrigation Levels On Soybean Production In Texas High Plains To Manage Diminishing Groundwater Levels, Vaishali Sharda, Prasanna H. Gowda, Gary Marek, Isaya Kisekka, Chittaranjan Ray, Pradip Adhikari

Nebraska Water Center: Faculty Publications

There is an increasing need to strategize and plan irrigation systems under varied climatic conditions to support efficient irrigation practices while maintaining and improving the sustainability of groundwater systems. This study was undertaken to simulate the growth and production of soybean [Glycine max (L.)] under different irrigation scenarios. The objectives of this study were to calibrate and validate the CROPGRO-Soybean model under Texas High Plains’ (THP) climatic conditions and to apply the calibrated model to simulate the impacts of different irrigation levels and triggers on soybean production. The methodology involved combining short-term experimental data with long-term historical weather data (1951–2012), …

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Transition Pathways To Sustainable Agricultural Water Management: A Review Of Integrated Modeling Approaches, Erin M.K. Haacker, Vaishali Sharda, Amanda M. Cano, R. Aaron Hrozencik, Agustin Nunez, Zachary Zambreski, Soheil Nozari, Garvey Engulu B, Smith, Lacey Moore, Sumit Sharma, Prasanna Gowda, Chittaranjan Ray, Meagan Schipanski, Reagan Waskom Dec 2018

Transition Pathways To Sustainable Agricultural Water Management: A Review Of Integrated Modeling Approaches, Erin M.K. Haacker, Vaishali Sharda, Amanda M. Cano, R. Aaron Hrozencik, Agustin Nunez, Zachary Zambreski, Soheil Nozari, Garvey Engulu B, Smith, Lacey Moore, Sumit Sharma, Prasanna Gowda, Chittaranjan Ray, Meagan Schipanski, Reagan Waskom

Nebraska Water Center: Faculty Publications

Agricultural water management (AWM) is an interdisciplinary concern, cutting across traditional domains such as agronomy, climatology, geology, economics, and sociology. Each of these disciplines has developed numerous process-based and empirical models for AWM. However, models that simulate all major hydrologic, water quality, and crop growth processes in agricultural systems are still lacking. As computers become more powerful, more researchers are choosing to integrate existing models to account for these major processes rather than building new cross-disciplinary models. Model integration carries the hope that, as in a real system, the sum of the model will be greater than the parts. However, …

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Gmaim: An Analytical Pipeline For Microrna Splicing Profiling Using Generative Model, Kan Liu Dec 2018

Gmaim: An Analytical Pipeline For Microrna Splicing Profiling Using Generative Model, Kan Liu

Department of Computer Science and Engineering: Dissertations, Theses, and Student Research

MicroRNAs (miRNAs) are a class of short (~22 nt) single strand RNA molecules predominantly found in eukaryotes. Being involved in many major biological processes, miRNAs can regulate gene expression by targeting mRNAs to facilitate their degradation or translational inhibition. The imprecise splicing of miRNA splicing which introduces severe variability in terms of sequences of miRNA products and their corresponding downstream gene expression regulation. For example, to study biogenesis of miRNAs, usually, biologists can deplete a gene in the miRNA biogenesis pathway and study the change of miRNA sequences, which can cause impression of miRNAs. Although high-throughput sequencing technologies such as …

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A Simple And Robust Approach To Reducing Contact Resistance In Organic Transistors, Zachary A. Lamport, Katrina J. Barth, Hyunsu Lee, Eliot Gann, Sebastian Engmann, Hu Chen, Martin Guthold, Iain Mcculloch, John E. Anthony, Lee J. Richter, Dean M. Delongchamp, Oana D. Jurchescu Dec 2018

A Simple And Robust Approach To Reducing Contact Resistance In Organic Transistors, Zachary A. Lamport, Katrina J. Barth, Hyunsu Lee, Eliot Gann, Sebastian Engmann, Hu Chen, Martin Guthold, Iain Mcculloch, John E. Anthony, Lee J. Richter, Dean M. Delongchamp, Oana D. Jurchescu

Chemistry Faculty Publications

Efficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts, namely the contact resistance. A large contact resistance can limit the operation of devices and even lead to inaccuracies in the extraction of the device parameters. Here, we demonstrate a simple and efficient strategy for reducing the contact resistance in organic thin-film transistors by more than an order of magnitude by creating high work function domains at the surface of the injecting electrodes to promote channels …

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Facepet: Enhancing Bystanders' Facial Privacy With Smart Wearables/Internet Of Things, Alfredo J. Perez, Sherali Zeadally, Luis Y. Matos Garcia, Jaouad A. Mouloud, Scott Griffith Dec 2018

Facepet: Enhancing Bystanders' Facial Privacy With Smart Wearables/Internet Of Things, Alfredo J. Perez, Sherali Zeadally, Luis Y. Matos Garcia, Jaouad A. Mouloud, Scott Griffith

Information Science Faculty Publications

Given the availability of cameras in mobile phones, drones and Internet-connected devices, facial privacy has become an area of major interest in the last few years, especially when photos are captured and can be used to identify bystanders’ faces who may have not given consent for these photos to be taken and be identified. Some solutions to protect facial privacy in photos currently exist. However, many of these solutions do not give a choice to bystanders because they rely on algorithms that de-identify photos or protocols to deactivate devices and systems not controlled by bystanders, thereby being dependent on the …

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Novel Materials Can Radically Improve Whole-System Environmental Impacts Of Additive Manufacturing, Jeremy Faludi, Cory M. Van Sice, Yuan Shi, Justin Bower, Owen M.K Brooks Dec 2018

Novel Materials Can Radically Improve Whole-System Environmental Impacts Of Additive Manufacturing, Jeremy Faludi, Cory M. Van Sice, Yuan Shi, Justin Bower, Owen M.K Brooks

Dartmouth Scholarship

Additive manufacturing often has higher environmental impacts per part than traditional manufacturing at scale, but new materials can enable more sustainable 3D printing. This study developed and tested novel materials for paste extrusion printing, and tested materials invented by others. Testing compared their whole-system environmental impacts to standard ABS extrusion, measured by life cycle assessment (LCA); testing also assessed material strength, printability, and cost. Materials were chosen for low print energy (chemical bonding, not melting), low toxicity, and circular life cycle (biodegradable, ideally sourced from waste biomaterial). Printing energy was reduced 75% (from 160 to 40 Wh/part), and embodied impacts …

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Revisiting The Paleomagnetism Of The Neoarchean Uauá Mafic Dyke Swarm, Brazil: Implications For Archean Supercratons, J. Salminen, E. P. Oliveira, Elisa J. Piispa, Aleksey Smirnov, R. I. F. Trindade Dec 2018

Revisiting The Paleomagnetism Of The Neoarchean Uauá Mafic Dyke Swarm, Brazil: Implications For Archean Supercratons, J. Salminen, E. P. Oliveira, Elisa J. Piispa, Aleksey Smirnov, R. I. F. Trindade

Michigan Tech Publications

The original connections of Archean cratons are becoming traceable due to an increasing amount of paleomagnetic data and refined magmatic barcodes. The Uauá block of the northern São Francisco craton may represent a fragment of a major Archean craton. Here, we report new paleomagnetic data from the 2.62 Ga Uauá tholeiitic mafic dyke swarm of the Uauá block in the northern São Francisco craton, Eastern Brazil. Our paleomagnetic results confirm the earlier results for these units, but our interpretation differs. We suggest that the obtained characteristic remanent magnetization for the 2.62 Ga swarm is of primary origin, supported by a …

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Digital Plasmonic Holography, Joseph W. Nelson, Greta R. Knefelkamp, Alexandre G. Brolo, Nathan C. Lindquist Dec 2018

Digital Plasmonic Holography, Joseph W. Nelson, Greta R. Knefelkamp, Alexandre G. Brolo, Nathan C. Lindquist

Physics and Engineering Faculty Publications

We demonstrate digital plasmonic holography for direct in-plane imaging with propagating surface-plasmon waves. Imaging with surface plasmons suffers from the lack of simple in-plane lenses and mirrors. Lens-less digital holography techniques, however, rely on digitally decoding an interference pattern between a reference wave and an object wave. With far-field diffractive optics, this decoding scheme provides a full recording, i.e., a hologram, of the amplitude and phase of the object wave, giving three-dimensional information from a two-dimensional recording. For plasmonics, only a one-dimensional recording is needed, and both the phase and amplitude of the propagating plasmons can be extracted for high-resolution …

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Energy Demand And Water Footprint Study Of An Agricultural Machinery Industry, Mantoam E,J., Mesfin Mekonnen, T.L. Romanelli Dec 2018

Energy Demand And Water Footprint Study Of An Agricultural Machinery Industry, Mantoam E,J., Mesfin Mekonnen, T.L. Romanelli

Daugherty Water for Food Global Institute: Faculty Publications

The intensification of agricultural production systems demands power, supplied by agricultural machinery, besides more agricultural inputs such as fertilizers, pesticides and seeds. Agricultural mechanization provides increase in the global production of food, fiber and bioenergy; and it brought economic benefits to producers, but causing larger energy consumption. Energy embodiment in agricultural machinery has been done in earlier studies, but data usually are from car industry. This study aimed to determine the energy demand and water footprint in a plant that assembles five types of agricultural machinery from a multinational manufacturer located in Piracicaba municipality in Sao Paulo state, Brazil. That …

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Improved Gas Sensing Performance Of Ald Azo 3-D Coated Zno Nanorods, P. Lin, X. Chen, K. Zhang, H. Baumgart Dec 2018

Improved Gas Sensing Performance Of Ald Azo 3-D Coated Zno Nanorods, P. Lin, X. Chen, K. Zhang, H. Baumgart

Electrical & Computer Engineering Faculty Publications

This paper reports an enhancement on the sensing performance of ZnO nanorod ethanol sensors with a new approach by utilizing nested coatings of Aluminum doped ZnO (AZO) thin films by Atomic Layer Deposition (ALD) technology. ZnO nanorods were grown by the hydrothermal method with the ZnO seed layer synthesized on Silicon wafers by ALD. To enhance the sensing performance of ZnO nanorod ethanol sensors, multiple coated AZO thin film 3-D coatings were deposited on the surface of the intrinsic ZnO nanorods by ALD.To investigate the sensing performance of the ZnO nanorods sensor for the detection of ethanol vapor, a gas …

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Fogfly: A Traffic Light Optimization Solution Based On Fog Computing, Quang Tran Minh, Chanh Minh Tran, Tuan An Le, Binh Thai Nguyen, Triet Minh Tran, Rajesh Krishna Balan Dec 2018

Fogfly: A Traffic Light Optimization Solution Based On Fog Computing, Quang Tran Minh, Chanh Minh Tran, Tuan An Le, Binh Thai Nguyen, Triet Minh Tran, Rajesh Krishna Balan

Research Collection School Of Computing and Information Systems

This paper provides a fog-based approach to solving the traffic light optimization problem which utilizes the Adaptive Traffic Signal Control (ATSC) model. ATSC systems demand the ability to strictly reflect real-time traffic state. The proposed fog computing framework, namely FogFly, aligns with this requirement by its natures in location-awareness, low latency and affordability to the changes in traffic conditions. As traffic data is updated timely and processed at fog nodes deployed close to data sources (i.e., vehicles at intersections) traffic light cycles can be optimized efficiently while virtualized resources available at network edges are efficiently utilized. Evaluation results show that …

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Investigation Of Electrolytic Flocculation For Microalga Scenedesmus Sp Using Aluminum And Graphite Electrodes, Shihong Liu, Husam A. Abu Hajar, Guy Riefler, Ben J. Stuart Dec 2018

Investigation Of Electrolytic Flocculation For Microalga Scenedesmus Sp Using Aluminum And Graphite Electrodes, Shihong Liu, Husam A. Abu Hajar, Guy Riefler, Ben J. Stuart

Civil & Environmental Engineering Faculty Publications

Electrolytic flocculation using non-sacrificial electrodes with flocculants added was studied on harvesting Scenedesmus sp. In order to optimize the operating conditions of the electrolytic flocculation process and to quantify the amount of flocculants added, aluminum electrodes were first used in the process. It was found that under optimal conditions, the microalgae removal efficiency using aluminum electrodes could reach 98.5%, while 34.2 mg L-1 of aluminum ions were released during the process. Different metal electrodes were also studied, but high microalgae removal efficiency was witnessed only using aluminum electrodes, indicating the influence of the aluminum ion in flocculation. When non-sacrificial …

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Deep Unsupervised Pixelization, Chu Han, Qiang Wen, Shengfeng He, Qianshu Zhu, Yinjie Tan, Guoqiang Han, Tien-Tsin Wong Dec 2018

Deep Unsupervised Pixelization, Chu Han, Qiang Wen, Shengfeng He, Qianshu Zhu, Yinjie Tan, Guoqiang Han, Tien-Tsin Wong

Research Collection School Of Computing and Information Systems

In this paper, we present a novel unsupervised learning method for pixelization. Due to the difficulty in creating pixel art, preparing the paired training data for supervised learning is impractical. Instead, we propose an unsupervised learning framework to circumvent such difficulty. We leverage the dual nature of the pixelization and depixelization, and model these two tasks in the same network in a bi-directional manner with the input itself as training supervision. These two tasks are modeled as a cascaded network which consists of three stages for different purposes. GridNet transfers the input image into multi-scale grid-structured images with different aliasing …

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Integrated Reward Scheme And Surge Pricing In A Ride-Sourcing Market, Hai Yang, Chaoyi Shao, Hai Wang, Jieping Ye Dec 2018

Integrated Reward Scheme And Surge Pricing In A Ride-Sourcing Market, Hai Yang, Chaoyi Shao, Hai Wang, Jieping Ye

Research Collection School Of Computing and Information Systems

Surge pricing is commonly used in on-demand ride-sourcing platforms (e.g., Uber, Lyft and Didi) to dynamically balance demand and supply. However, since the price for ride service cannot be unlimited, there is usually a reasonable or legitimate range of prices in practice. Such a constrained surge pricing strategy fails to balance demand and supply in certain cases, e.g., even adopting the maximum allowed price cannot reduce the demand to an affordable level during peak hours. In addition, the practice of surge pricing is controversial and has stimulated long debate regarding its pros and cons. To address the limitation of current …

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Credit Assignment For Collective Multiagent Rl With Global Rewards, Duc Thien Nguyen, Akshat Kumar, Hoong Chuin Lau Dec 2018

Credit Assignment For Collective Multiagent Rl With Global Rewards, Duc Thien Nguyen, Akshat Kumar, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

Scaling decision theoretic planning to large multiagent systems is challenging due to uncertainty and partial observability in the environment. We focus on a multiagent planning model subclass, relevant to urban settings, where agent interactions are dependent on their collective influence'' on each other, rather than their identities. Unlike previous work, we address a general setting where system reward is not decomposable among agents. We develop collective actor-critic RL approaches for this setting, and address the problem of multiagent credit assignment, and computing low variance policy gradient estimates that result in faster convergence to high quality solutions. We also develop difference …

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Automatically `Verifying’ Discrete-Time Complex Systems Through Learning, Abstraction And Refinement, Jingyi Wang, Jun Sun, Shengchao Qin, Cyrille Jegourel Dec 2018

Automatically `Verifying’ Discrete-Time Complex Systems Through Learning, Abstraction And Refinement, Jingyi Wang, Jun Sun, Shengchao Qin, Cyrille Jegourel

Research Collection School Of Computing and Information Systems

Precisely modeling complex systems like cyber-physical systems is challenging, which often render model-based system verification techniques like model checking infeasible. To overcome this challenge, we propose a method called LAR to automatically ‘verify’ such complex systems through a combination of learning, abstraction and refinement from a set of system log traces. We assume that log traces and sampling frequency are adequate to capture ‘enough’ behaviour of the system. Given a safety property and the concrete system log traces as input, LAR automatically learns and refines system models, and produces two kinds of outputs. One is a counterexample with a bounded …

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Co-Location Resistant Virtual Machine Placement In Cloud Data Centers, Amit Agarwal, Nguyen Binh Duong Ta Dec 2018

Co-Location Resistant Virtual Machine Placement In Cloud Data Centers, Amit Agarwal, Nguyen Binh Duong Ta

Research Collection School Of Computing and Information Systems

Due to increasing number of avenues for conducting cross-virtual machine (VM) side-channel attacks, the security of public IaaS cloud data centers is a growing concern. These attacks allow an adversary to steal private information from a target user whose VM instance is co-located with that of the adversary. To reduce the probability of malicious co-location, we propose a novel VM placement algorithm called “Previously Co-Located Users First”. We perform a theoretical and empirical analysis of our proposed algorithm to evaluate its resource efficiency and security. Our results, obtained using real-world cloud traces containing millions of VM requests and thousands of …

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Early Prediction Of Merged Code Changes To Prioritize Reviewing Tasks, Yuanrui Fan, Xin Xia, David Lo, Shanping Li Dec 2018

Early Prediction Of Merged Code Changes To Prioritize Reviewing Tasks, Yuanrui Fan, Xin Xia, David Lo, Shanping Li

Research Collection School Of Computing and Information Systems

Modern Code Review (MCR) has been widely used by open source and proprietary software projects. Inspecting code changes consumes reviewers much time and effort since they need to comprehend patches, and many reviewers are often assigned to review many code changes. Note that a code change might be eventually abandoned, which causes waste of time and effort. Thus, a tool that predicts early on whether a code change will be merged can help developers prioritize changes to inspect, accomplish more things given tight schedule, and not waste reviewing effort on low quality changes. In this paper, motivated by the above …

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